LPIC-2 Linux Kernel and System Startup Practice Question
Which TWO of the following are valid methods to modify kernel parameters at runtime without rebooting?
⚠ Common exam trap
Many exam-takers confuse persistent configuration methods (like editing /etc/sysctl.conf or kernel command line) with runtime modification methods, or they mistakenly think loading a module with modprobe is equivalent to modifying kernel parameters.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Writing to files in /proc/sys/ using echo
The /proc/sys/ directory exposes kernel tunable parameters as virtual files, and writing a new value to these files (e.g., echo 1 > /proc/sys/net/ipv4/ip_forward) immediately changes the corresponding kernel parameter at runtime without requiring a reboot. This is a direct interface to the kernel's sysctl mechanism.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Using modprobe to load kernel modules with parameters
Why it's wrong here
modprobe loads modules, not modifies existing parameters.
- ✗
Editing /etc/sysctl.conf and running sysctl --system
Why it's wrong here
This applies settings from files, but it's not a direct runtime modification.
- ✓
Writing to files in /proc/sys/ using echo
Why this is correct
Writing directly to /proc/sys/ files changes parameters immediately.
- ✓
Using the sysctl command to set parameters
Why this is correct
sysctl modifies parameters in /proc/sys/ immediately.
- ✗
Adding parameters to the kernel command line in /etc/default/grub
Why it's wrong here
This requires a reboot to take effect.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This LPIC-2 practice question is part of Courseiva's free LPI certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the LPIC-2 exam.